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(11) | EP 2 639 951 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Flyback converter |
| (57) In a flyback converter (20 using primary side sensing to sense the output voltage
for regulation feedback a comparator (36) on the primary side detects whether the
output voltage has exceeded a predetermined regulated voltage by a first threshold
to detect an over-voltage condition, resulting from a current generated by the converter
exceeding the load current. Triggering of the comparator causes the converter to enter
a non-switching sleep mode, whereby the output voltage droops over a period of time.
When the output voltage has drooped below the predetermined regulated voltage by a
second threshold, a synchronous rectifier is controlled (28) to turn on, then off,
to generate a pulse in the primary winding. Upon detection of the pulse, the sleep
mode is terminated, and normal operation resumes until a regulated voltage is achieved
or until the first threshold is again exceeded by the output voltage.
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